The Pacific Diver (Gavia pacifica), known in North America as the Pacific Loon, is a medium-sized member of the loon, or diver, family. It may be conspecific with Black-throated Diver, which it closely resembles.

It breeds on deep lakes in the tundra region of Alaska and northern Canada as far east as Baffin Island, and in Russia east of the Lena River.

Unlike other loons, this bird may migrate in flocks. It winters at sea, mainly on the Pacific coast, or on large lakes over a much wider range, including China, Japan, North Korea, South Korea, USA and Mexico. It has occurred as a vagrant to Greenland, Hong Kong and Great Britain.

This species was spotted in Europe on January, 2007, with an individual in Great Britain near Farnham, North Yorkshire.

Breeding adults are like a smaller sleeker version of Great Northern Diver. They have a grey head, black throat, white underparts and chequered black-and-white mantle. Non-breeding plumage is drabber with the chin and foreneck white. Its bill is grey or whitish and dagger-shaped. In all plumages, lack of a white flank patch distinguishes this species from the otherwise very similar Black-throated Diver.

This species, like all divers, is a specialist fish-eater, catching its prey underwater. It flies with neck outstretched.